Multiple revolution limit stop device



Feb. 12, 1957 E. O. KOLLMORGEN MULTIPLE REVOLUTION LIMIT STOP DEVICE Filed March 18, 1953 FIGJ.

' INVENTOR. I E RNS T O. KOLLMORGEN BY HI ATTORNEYS.

llnited States hate MlULTIPLE REVOLUTION Lllt IIT STGP DEVllCE Ernst t). Kollmorgen, Amherst, Mass, assignor to Kellmorgen Optical Corporation, Northampton, ltlass, a corporation of New York Application March 18, 1953, Serial No. 343,1?35

6 Claims. (Cl. 74-10.2)

This invention relates to mechanisms for limiting the relative rotation of a pair of rotary elements and it relates particularly to a limit stop mechanism which enables a pair of relatively rotatable elements to rotate nearly two revolutions in either direction before being brought to a stop.

in many diiierent kinds of apparatus, such as optical instruments, radio tuning mechanisms, metering valves, potentiometers, steering controls and the like, it is quite common to have rotary elements, such as control knobs, dials, or hand wheels which are provided with limit stops that limit their angular movement to less than 360. The limit stop usually consists of a pin fixed to one of the elements which engages in a groove in the other element, the groove extending through an arc of less than 360. The extent of the unobstructed groove, of course, limits the movement of the pin and the knob or dial to the desired angle of rotation.

it would be most advantageous if it were possible to provide the dials, knobs or the like of the above-described devices with stop means which permit the knobs, dials or the like to rotate through more than one revolution. The increased angular movement obtained thereby would permit a more critical control of the operation of the device or a more extended range of control and it would also enable a better spacing of the indicia marks on the scales and the like on the knobs, dials or control handles.

The present invention provides a simple and eifective limit stop mechanism which permits a pair of relatively rotatable elements to rotate more than one revolution between the limit stops thereof.

More particularly, the limit stop mechanism includes a circular track in one of the rotary elements, the track being partially obstructed at one point and the other rotary element having a member, such as a pin, lug or the like, extending into and movable along the track, but not sufiiciently far to engage the obstruction in the track. The two members thereby can rotate relatively through any desired angle without interference between the obstruction and the lug or pin. The relative rotation of the two elements can, in accordance with the present invention, be limited to slightly less than two revolutions by interposing a stop member, such as a ball or slide member in the track so that it engages between the obstruction and the pin or lug and prevents them from passing each other. The obstruction and the pin or lug up against the stop member at one limit of relative rotation but permit the rotary elements to which they are attached to be rotated away from that limit position almost two complete revolutions before the pin or lug strikes the stop member and the latter is brought up against the obstruction in the track. In this way, it is possible to nearly double the relative rotary movement of a pair of rotatable elements between limit stops without complicating the relations between these elements.

For a better understanding of the present invention reference may be had to the accompanying drawing in which:

2,780,941 Patented Feb. 12, 1957 Fig. 1 is a view in longitudinal sectionthrough a device'including a' control knob and a shaft and in which the relative movement of the control knob is limited by a mechanism embodying the present invention; and

Fig. 2 is a view in section taken on line 2-2 of Fig. 1.

The mechanism illustrated in Figs. 1 and 2 of the drawing is an adjusting knob for a telescopic rifle sight. However, the limit stop means described hereinafter can be used with equal facility in other optical instruments, controls for valves, radio tuners, electrical instruments of various types and many other devices in which rotary knobs or handles are required for adjustment or control.

As shown in Figs. 1 and 2, the adjusting mechanism includes a knob 10 mounted on a shaft II which may extend into the interior of a casing section 12 of a telescopic rifle sight, the knob 10 being used to adjust the reticle in the sight for range or deflection, as may be desired. Fixed to the casing section 12 and concentric with the shaft ill is a sleeve 13 in which the shaft 11 rotates. The knob it has a downwardly extending skirt or collar which surrounds and engages the sleeve 13. The struc ture of the knob and the supporting sleeve can be modified as desired.

The limit stop mechanism for the adjusting knob 10 includes an annular track formed by a groove 15 extending circumferentially around the outside of the sleeve 13. intersecting the bottom of the groove is a stop member such as a small pin 16, which extends into the groove about one-half the depth of the groove or less and partially obstructs the groove. The pin 16 may be mounted in a bore 17 which is drilled lengthwise of the sleeve 13 and intersects the bottom of the groove 15.

The knob 19 is provided with a radial bore 18 in which is removably mounted a stop member such as a pin 19 having a reduced inner end 20 and a shoulder 21 thereon which limits the inward movement of the pin in the bore 18. The inner reduced end 20 of the pin extends into the groove 15 a distance insufficient to allow the end of the pin 19 to engage the pin 16 which partially obstructs the groove. The pins 16 and 19 do not strike or interfere with each other. In order to limit the relative rotation of the knob 10, a limit member such as a ball 23 is placed in the groove, the ball being only slightly smaller in diameter than the depth of the groove and large enough so that it will jam between the stop pins 16 and 19 to prevent them from passing by each other. it will be understood that the ball 23 is placed in the groove 15 before the knob 10 is slipped over the sleeve The pin 19 is then inserted in the bore 18 and the pin 19 may be locked in position in any suitable way, such as, for example, by means of a sleeve 24 which is slidable on the knob 10 to cover and uncover the bore 13.

With the pin l9, the ball 23 and the pin 16 in the position shown in Fi 2, the knob 10 cannot be rotated in a clockwise direction. However, it can be rotated almost a complete revolution in a counterclockwise direction before the pin w again strikes the ball 23. in this position both of the pins 16 and 19 are on the same side of the ball so that further rotation of the knob 10 in a counterclockwise direction is permitted, the ball being pushed ahead of the pin 19 until the ball 23 comes up against the pin 16. inasmuch as the ball cannot pass by the pin 16 and the pin 19 cannot pass the ball 23, counterclockwise movement of the knob is stopped after almost two revolutions from the position shown in Fig. 2.

While the invention is illustrated in connection with an adjusting knob for a telescopic sight and in which the groove or track is formed circumferentially around a sleeve, it will be understood that the groove may be equally well formed in the inner surface of the knob or partly in the sleeve and partly in the knob or in the outer end of the sleeve 13 or. in the inner flat surface of the 3 knob, and that the obstruction extending into the track and the stop pin or lug on the knob can be appropriately positioned to limit relative rotation of the elements in the manner described above.

it will be understood, of course, that the track may be formed with a permanent obstruction rather than a removable pin and that a lug integral with the knob may be used instead of the removable pin 19, as shown in Figs. 1 and 2. Moreover, any suitable limit device, such as a slide bar, rod or the like, may be used instead of the ball 23 so long as it is movable freely along the groove and is of sufliciently large diameter or thickness to prevent the two elements from passing by each other at the intended limits of rotation.

From the preceding description, it will be clear that the embodiment of the invention described above is illustrative and that it should not be considered as limiting the scope of the following claims.

I claim:

l. A limit stop device comprising a pair of relatively rotatable members, a circular track on at least one of said members, said track being concentric with the axis of relative rotation of said members, a limit member movable freely along said track, and stop members fixed to said rotatable members and extending adjacent to said track, said stop members being spaced apart in all positions of said rotatable members, both of said stop members being engageable with the limit member to limit the relative rotation of said rotatable members to positions in which said stop members engage the opposite sides of said limit member.

2. A limit stop device comprising a pair of relatively rotatable concentric elements, one of said elements having a substantially cylindrical surface with a groove therein concentric with the axis of relative rotation of said elements and facing toward the other element, a stop member on each element extending into said groove, said stop members being located out of each others paths of movement, and a limit member in and movable along said groove, said limit member being engageable with said stop members to limit relative rotation of said elements to more than one but less than two revolutions.

3. A limit stop device comprising a pair of relatively rotatable elements, one of said elements having a circular groove therein concentric with the axis of relative rotation of said elements and interposed between said elements, stop members on said elements extending into said groove and being spaced apart in all positions of the said members a distance sufficient to keep them out of engagement with each other, and a limit member movable along said groove and engageable by both of said stop members to limit the relative rotation of said elements in either direction to about two revolutions.

4. The device set forth in claim 3 in which said stop members are pins on said elements extending into said groove and the limit member is a ball having a diameter too large to pass between said pins.

5. The device set forth in claim 3 in which one of said relatively rotatable elements is fixed and the other includes a collar and said groove extends circumferentially around said fixed member and is covered by said collar.

6. A limit stop device comprising a knob having a depending flange thereon and a shaft within and concentric with said flange, said flange having a substantially radial opening therethrough, a sleeve rotatably receiving said shaft and fitting telescopically in said flange, said sleeve having a groove extending around it and covered by said flange, a first stop member on said sleeve extending into and partially blocking said groove, a ball freely movable along said groove from one side of said stop to its other side and having a diameter about as great as the depth of the groove, a second stop member removably mounted in the said flange opening and projecting into said groove to secure the knob to the sleeve and to engage and move said ball in said groove, said second stop member being spaced from said first stop member in all positions of said knob and sleeve, and a member detachably mounted on said knob and overlying the outer end of said opening to retain said stop member in said opening.

References Cited in the file of this patent UNITED STATES PATENTS 822,057 Krebs May 29, 1906 1,339,052 Bauer May 4, 1920 2,458,859 Kestell Ian. 11, 1949 

